second exam chem 256 – organic chemistry ii prof. bastin ... · bastin – exam #2 chem 256 -...

Second Exam CHEM 256 – Organic Chemistry II

Prof. Bastin Spring 2016

Name ___________________________ Section ________

1. DO NOT START this exam until you are instructed to begin.

2. There are ELEVEN pages including this cover sheet and the IR frequency table - make sure they are all here!

3. Provide CLEAR, CONCISE answers using unambiquous, carefully drawn structures and mechanisms for the appropriate questions. Be sure to read each question VERY CAREFULLY.

4. Do not provide mechanisms for synthesis and product prediction problems.

5. You may only use a pen or pencil and the materials provided in this packet on this exam.

6. If you have papers and/or books with you, they are to be left on the floor AT THE

FRONT OF THE ROOM. If you need scrap paper please ask.

7. Cell phones must be OFF and placed on the table at the FRONT of the ROOM.

1) _______/12 pts 2) _______/12 pts

3) _______/10 pts

4) _______/12 pts Total: ________/100 pts 5) _______/8 pts

6) _______/10 pts 7) _______/12 pts

8) _______/24 pts

Bastin – Exam #2 Chem 256 - Spring 2016

2

1) (12 pts) Provide structures for the following compounds.

a) o-bromobenzaldehyde

b) p-diaminobenzene c) o-methylphenol d) m-xylene e) 2-hydroxy-3-bromo-5-butylbenzoic acid

f) 3-chloroaniline


3

2) (12 pts) Provide either common or IUPAC names for the following compounds. a)

b)

c)

d)

e)

f)

NH2

COOH

ClCl

OH

OCH3

Br


4

3) (10 pts) Rank the following compounds in order of decreasing acid strength, from lowest pKa to highest pKa (be sure your order is clearly indicated). Explain.

A B C D E


5

4) (12 pts) Predict whether each of the following molecules would be aromatic, non-aromatic, or anti-aromatic. Explain your reasoning. (a) (b) (c) (d)

5) (8 pts) Using a Frost circle, draw the π MO energy diagram for the molecule below. Fill

the orbitals with the appropriate number of π elections. Based on this diagram, should the molecule be aromatic, non-aromatic, or anti-aromatic? Explain.

NH

NH2N


6

6) (10 pts) What differences in the IR spectra of the reactant and product in each of the following transformations would enable you to tell that each reaction took place? Be specific and give numbers. Include all distinguishing peaks.

(a)

(b)

(c)

OH

NH2 NH

O OH


7

7) (12 pts) For each of the following IR spectra (a-d) there is a choice of three possible types of compounds. For each spectrum, choose the most appropriate class of compound. Explain your reasoning by noting the presence or absence of characteristic bands in the spectrum.

a) alcohol, carboxylic acid, or phenol

b) aldehyde, ester, or ketone

c) 1-alkyne, symmetrical internal alkyne, or nitrile

PR0BLEM 15.34 (C0lrTrr{UED).l Microns (F)

22 2.12.A2.A 3 3,5 44,5 5 5.5 0 7 I 910 11 12131a15t0lEm225

AlcoholCarboryllc acldPhenol

a 2.6 2.8 3 3.5 a 4.5

2 AldehydeEsterKetone2.2 2,4 2,4 2,4 3 3.5 4 4.5

Microns 0r)5 5.5 6 7 8 I10 t l 1?!3 l4t5r6.r l t | i

Microns 0r)5 5.6 6 7 6 I t0 1t 12t14r5r! 'a

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Micmns (p)22 2.42.62.8 3 3-5 a4.5 5 5.56 7 E 910 11 12131ar5r61E626

@ @ m 2m ro@rmlm101&1@Wavonumbs (cr1)

4 Primary amidePrimary amineNitro compound

1 2.6 2.8 g 3.3 a a.!Microns (F)

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PR0BIEM 15.35 For each of the following lR spectra (1-5)there is a choice of three possible types of compounds. Foreach spectrum, choose the most appropriate class of com-pound. Explain your reasoning by noting the presence or ab-sence of characteristic bands in the soectrum.

@ @ ru 2m m@1m1@1@1m1@Wav€numbs (cr1)

5 AnhydrideGarboxylic acidEster Microns (d2.2 2.42.82.5 3 3.5 44.5 5 5.5 6 7 I 910 11 12131. ' ! ! .

@ @ ru 2m ru@rmr&tolru1mWav6numb6r (cm1)

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a 2.6 2.8 3 3.5 a 4.5




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1 2.6 2.8 g 3.3 a a.!Microns (F)

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8

d) anhydride, carboxylic acid, or ester

8) (24 pts) Devise (below and on the following blank page) a synthesis for the following transformations using any reagents that we have discussed, the indicated starting material, and any other stable organic starting materials needed. If you need more space, please use the back of this sheet and direct me there. For FULL credit be sure to show the retrosynthetic analysis AND the complete synthesis.

a)


22 2.12.A2.A 3 3,5 44,5 5 5.5 0 7 I 910 11 12131a15t0lEm225


a 2.6 2.8 3 3.5 a 4.5




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from

CN

CN

Bastin –Exam #2 Chem 256 - Spring 2016

9

b)

from


10


11

Functional Group Frequency (cm-1) Intensity and Comments Alkanes

C–H C–C

2980-2850 1480-1420

medium to strong medium

Alkenes =C–H stretch =C–H bend C=C

3150-3000 980-960 (trans) 730-665 (cis) 1680-1600

medium; very weak for trans strong strong weak to medium

Alkynes ≡C–H C≡C

3350-3300 2260-2100

strong weak to medium

Alkyl halides C–Cl C–Br C–I

800-600 600-500 500

strong strong strong

Alcohols O–H C–O

3650-3300 1350-1050

strong and broad strong

Amines N–H C–N

3500-3100 ~1200

medium and strong; 1° amines-2 bands; 2° amines-1 band medium

Aromatics C–H stretch C–H bend C=C

3080-3020 900-730 1650-1580

weak to medium strong weak to medium

Carbonyls (C=O) Ketones Aldehydes Esters Amides Acids Acid Anhydride Acid Chlorides

1730-1700 1730-1700 1750-1735 1680-1630 1730-1700 1850-1740 1820-1770

strong strong; also has a O=C-H doublet at ~2700 & 2800 cm1 strong; also has C–O stretch strong; 1° and 2° amides also have N-H stretch strong; also has O–H stretch strong; doublet strong

Nitrile (C≡N) 2200-2250 medium Nitro (NO2) Doublet at:

1570-1550 & 1380-1360

strong

second exam chem 256 – organic chemistry ii prof. bastin ... · bastin – exam #2 chem 256 -...

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